1. Field of the Invention
This invention relates to an arrangement for protecting components such as valves and control units incorporated in a subsea structure particularly for hydrocarbon production. More specifically, the invention is directed to a protective roof arrangement intended to protect components in the subsea structure against objects dropped from above or moving along the seabed, such as trawls or the like.
The present subsea structure consists of a template which is secured to the seabed and modules retrievable to the surface for maintenance. There are different types of modules, all designed according to a similar pattern so as to interface with installation, maintenance ,and inspection tools. They are "integrated modules", in that, although some parts of the module are retrievable separately from the rest of the module, the module can be installed in one run with all of its components;.mounted thereon. As described hereinafter, these integrated modules include protective roof elements arranged in a specific manner according to the present invention.
2. Discussion of the Related Art
When a subsea station is in production mode, all the units constituting it are or may be installed onto the template main structure. It is important during production periods and also when other operations are performed on or near the subsea station, that, objects, dropped into the water or moved along the seabed, for example in connection with fishing operations, do not interfere with the normal functioning of the subsea station or even cause damage to the station.
For achieving protection similar to what is contemplated here, more conventional designs propose a separate roof, either integrated and hinged into the template structure, or run after installation of the necessary equipment on the template. This results in additional and more delicate operations than what is made possible by the solution according to this invention, as will appear from the following description. One particular drawback with a conventional design, is an increased risk of objects dropped on a module when it is retrieved, since there is no roof protecting it. An example of such known design for protective roofing for subsea installations is found in U.S. Pat. No. 4,273,472, issued Jun. 16, 1981, to A. Piazza. Published GB Patent Application No. 2,195,686 shows an example of a typical subsea station or template structure without any roofing.